The firethorn likes a sunny or semi-shaded position during the growing season. It needs a certain amount of sunlight to produce fruit but should be protected from extreme heat and sun in hotter climates. Pyracanthas are frost-hardy, but when they are planted in containers it is advisable to protect them from strong frost and cold wind. A cold frame is a good place for winter protection.
Always keep the rootball slightly moist. In summer, when the tree produces flowers and fruits, it needs a lot of water and must not dry out. But also take care not to overwater the firethorn. In winter it needs less water.
Apply solid organic fertilizer every four weeks or use a liquid fertilizer every week during the growing season. Use a balanced fertilizer with sufficient phosphorous and potassium to promote flowering and fruit development.
Pruning and wiring
Spring or late summer is a good time to thin out a dense canopy and remove dead parts. New shoots are trimmed back to two leaves during the growth period when they have elongated. Even hard pruning is tolerated and the Pyracantha bonsai will bud willingly from old wood, provided that it is healthy and vigorous. Large leaves can be removed at any time. Most shaping can be done with scissors.
Pruning and wiring
Wiring is possible but beware of the thorns. Older branches of Pyracantha Bonsai are stiff and brittle, but younger twigs are flexible and can be shaped easily. If you want to do a lot of wiring on a firethorn it could be wise to cut off the thorns first. The use of guy wires can sometimes be a better option.
Repot the firethorn tree every two years and older trees every three to five years in early spring. It takes root pruning well and has no special demands concerning the soil. Use a well-draining standard soil mix. The firethorn can grow in slightly acidic, neutral or even alkaline soils.
The firethorn tree can be propagated from seed, cuttings, or air-layering. Semi-hardwood cuttings can be taken in summer.
Pests and diseases
The firethorn can be attacked by various pests and diseases. Aphids, scale, spider mites, leaf miners, and caterpillars can occur as well as fire blight, which is a bacterial infection, or the fungal infections scab or sooty mold. Use a specific pesticide in case of an infestation. Root rot can occur when the tree is overwatered.